With prior-art known free-running or slip clutches, torque transmission takes place by means of pawls, coupling bodies, or balls that fit between the input and output elements. For example with a bicycle free-running hub, balls are used so that if the input shaft turns faster than the housing, the balls are urged outward by the shape of grooves in the shaft and wedge solidly between the input and output shafts so that the housing is entrained. If on the contrary the housing turns faster than the input shaft, the balls move inward in the grooves so that there is no force transmission.
All these clutches have in common that the coupling element is positioned radially between the input and output elements where it either in the coupling position blocks relative movement between the input and output elements or in the free-running position permits relative movement of the input element and the output element.
In order to make the free-running clutch simpler and cheaper to manufacture even with these functions, German 2,452,650 proposes a free-running clutch with nonround coupling bodies between an inner and an outer coupling ring and out of contact when slipping with the faster coupling ring, the coupling bodies each being held against the faster ring when slipping by means of a part-cylindrical surface parallel to the body axis. The clutch has an inner coupling ring fixed on a shaft and a concentric outer coupling ring on another shaft concentric with the inner ring. The gap between the two coupling rings holds nonround coupling bodies of which each has a bore extending parallel to its pivot axis and by means of which it is mounted on a hardened pivot bolt. The ends of the pivot bolt projecting past the coupling bodies are each force fitted in a bore seat of an inner annular flange of the outer coupling ring. The bore in the one flange and the surface formed by the pivot bolt also form the coupling surface for the outer coupling ring.
WO 95/03503 describes a steplessly or almost steplessly variable positive-contact planetary-gear transmission with input and output elements that have several wheels that together form a planet wheel that are in permanent mesh with a sun wheel. The ratios of the effective radii of the planet wheel and the sun wheel and the relative eccentric positions of the planet wheel and the sun wheel which can be varied by various means determine the speed relationship between the input and output elements. The wheels forming the planet wheel cyclically run, when set eccentrically to the sun wheel, through a torque-transmitting load path and a load-free path, the wheels rotating both about the planet-wheel axis and via respective one-way clutches about their own axes. On moving from the load-free path to the arcuate load path the wheels as a result of meshing block their actual rotation and transmit the applied torque. Any irregularity in the torque transmission is compensated for by variation of the radii determined by the load arc and/or the effective tangential component in a cyclical manner.